Studies are in progress to explore and characterize the changes that occur in hepatic RNA metabolism at critical stages in the development of chemically-induced hepatomas. The carcinogens N-Acetylaminofluorene and N,N-diethylnitrosamine will be administered to rats in regimens that will produce preneoplastic lesions and hepatocellualr carcinomas. Closely related, though non-carcinogenic agents, will be used to serve as comparisons for these carcinogenic compounds. RNAs extracted from nuclei and cytoplasm of neoplastic, preneoplastic and normal proliferating hepatic tissue will be compared for differences in their rate of synthesis, size distribution, transport to the cytoplasm, distribution in the cytoplasm, and functional capabilities. A most important aspect of this work will be to correlate changes in the nature of the sequences of nuclear and cytoplasmic RNAs with histologic progression of the tumors. BIBLIOGRAPHIC REFERENCES: Austin, G.E. and Moyer, G.H. Early Changes in Hepatic RNA Synthesis and Distribution in Rats Fed Acetylaminofluorene. Proc. Amer. Assoc. Cancer Res. 18: 1977 (abs). Moyer, G.H. and Austin, G.E. The Acute Effects of N-hydroxy Acetylaminofluorene on Rat Liver Protein Synthesis. Fed. Proc. 36:349, 1977 (abs).